Just think of any 2 number that multiply to 10, then just add really small decimal values.
It would be 4-15x
sorry if not
Let
x-------> the length side of the poster
y-------> the width side of the poster
we know that
Area of the poster is equal to
-------> equation 
Area of the printed area is equal to
----> equation 
substitute equation
in equation 
![Aprinted=[210]-3x-2*[\frac{210}{x}]+6](https://tex.z-dn.net/?f=%20Aprinted%3D%5B210%5D-3x-2%2A%5B%5Cfrac%7B210%7D%7Bx%7D%5D%2B6%20%20)
using a graph tool
Find the vertex of the graph
The vertex of the graph is the point that represent the value of x for the largest printed area
see the attached figure
the vertex is the point 
the largest printed area is 

find the value of y

therefore
the answer is
The dimensions of the poster are 
Substitute the value of the variable into the equation and simplify.
The answer should be D
Sorry if I'm wrong
The y intercept is 40 and it means that at zero hours you have a score of 40(basically where you start out )